1. Field of the Invention
This invention relates to a granular adsorbent having a high uptake capacity for liquid ingredients of detergents and cleaning preparations, and in particular for liquid nonionic surfactants. The granular adsorbent of the present invention is particularly suitable for use in low-phosphate or phosphate-free detergents and cleaning preparations.
2. Description of Related Art
It is known that nonionic surfactants have a very high detergent power, thus making them particularly suitable for use in low-temperature detergents or 60.degree. C.-detergents. Unfortunately, in the standard spray-drying process generally used for manufacturing detergents, the nonionic surfactants cannot be used in an amount which significantly exceeds about 8 to 10% by weight, otherwise there is excessive pluming and waste of the surfactant in the offgases of the spray-drying towers, and the spray dried powder shows unsatisfactory flow properties. For this reason, processes have been developed in which the liquid nonionic surfactant is mixed with previously spray-dried powder or the surfactant is sprayed onto a carrier substance. Proposed carrier substances include spray-dried phosphates, borates or perborates, sodium aluminosilicates (zeolites), silica (Aerosil.RTM.) and the like.
Unfortunately, these known carriers have certain disadvantages. Phosphates are often undesirable because of their eutrophicating property. Borates, perborates and zeolites typically have only a limited uptake capacity for liquids. Other adsorbents, such as kieselguhr and Aerosil.RTM., increase the amount of ash in the detergent and thus on the material to be cleaned, without providing a detergent effect.
U.S. Pat. Nos. 3,849,327; 3,886,098 and 4,269,722 describe free flowing detergent compositions made by spray drying an aqueous builder salt mixture, optionally containing an anionic surfactant or a small amount of a nonionic surfactant. Suitable builder salts include phosphates, carbonates, silicates and the like. The bulk of the nonionic surfactant then is applied to the spray dried adsorbent powder, e.g., by spraying the liquid surfactant onto the powder in a rotating drum. In Great Britain No. 2,095,274, a complex, low-silicate, adsorbent carrier is described prepared by spray drying an aqueous mixture of a zeolite, bentonite and known water soluble builders and optionally containing an anionic surfactant or a small amount of a polyacrylate.